Rare heart disease; cor triatriatum sinister in a resource-limited setting: a case report

¹Cardiology Department University Hospital Agadir, Medical School of Medicine and Pharmacy Ibn Zohr University, Agadir, Morocco

^&Corresponding author
Soukaina Aabbar, Cardiology Department University Hospital Agadir, Medical School of Medicine and Pharmacy Ibn Zohr University, Agadir, Morocco

Introduction    

Cor triatriatum is a rare cardiac congenital heart defect, with a rate of 0.1-0.4%. It is a condition in which one of the atria is abnormally divided into two separate chambers by a thin fibromuscular membrane [1]. In most cases, it affects the left atrium, a condition known as cor triatriatum sinister. Here, the membrane separates the chamber receiving blood from the pulmonary veins from the true left atrial chamber that connects to the mitral valve and the left ventricle. The much rarer form, cor triatriatum dexter, involves the right atrium and usually results from the persistence of embryonic venous structures that normally regress. The membrane may have one or more fenestrations, and the degree of blood flow obstruction depends on their number and size [1]. The clinical presentation is highly variable, and may range from a complete asymptomatic state and remain undiagnosed for decades, to sudden death. The diagnosis is so challenging, particularly in adulthood, the conditions mimics more common acquired cardiac pathologies, which can lead to misdiagnosis. This case reflects the tragic consequences of a delayed diagnosis of a congenital heart defect in an adult patient, worsened by the lack of adequate diagnostic and surgical resources. Despite being a potentially curable condition, the absence of advanced specialized care led to a missed opportunity for timely intervention.

Patient and observation     

Patient information: a 28-year-old Moroccan woman presented to the hospital with worsening dyspnea and oedema. She has no medical history.

Clinical findings: the clinical examinations revealed a remarkable cyanosis, oxygen saturation of 89% on room air, a diastolic murmur, bibasilar crackles, tachycardia, with no peripheral pulses´ deficit. There was mild jugular venous distension, bilateral lower limb edema, and a mildly enlarged, tender liver was palpated.

Timeline of current episode: based on the patient's clinical signs, an initial diagnosis of cardiac decompensation was made, and treatment with diuretics and oxygen therapy was initiated.

Diagnostic assessment: the electrocardiogram (EKG) revealed atrial fibrillation. A chest X-ray showed signs of volume overload. Transthoracic echocardiography revealed a thin, fibromuscular membrane within the left atrium; this finding is highly suggestive of cor triatriatum sinister, dividing it into two distinct chambers, and no visible interatrial communication, with an obstructive gradient of 7mmHg. The left ventricle appeared small but with preserved ejection fraction. The right ventricle was dilated with prominent trabeculations. The estimated pulmonary artery systolic pressure was approximately 100 mmHg, indicating a high probability of pulmonary hypertension, moderate mitral valvular regurgitation. The laboratory tests showed an elevated NT pro BNP, liver dysfunction, and anemia (Figure 1, Figure 2).

Diagnosis: the final diagnosis was cor triatriatum sinister, a rare congenital cardiac anomaly, complicated by secondary pulmonary hypertension and atrial fibrillation. The prognosis was poor, not only because of the severity of the obstruction and its hemodynamic complications, but above all because of the lack of specialized medical infrastructure to provide adequate surgical care.

Therapeutic interventions: the initial care focused on medical stabilization, including the management of atrial fibrillation and acute heart failure, which led to temporary clinical improvement.

Follow-up and outcome of interventions: the patient has been discharged due to lack of access to advanced cardiac surgical facilities and the absence of any viable referral pathway to a specialized center, definitive treatment could not be offered. Unfortunately, she was reported to have died several weeks later.

Patient perspective: it was impossible to gather any direct insights from the patient due to the tragic outcome. Despite a potentially curable condition, the clinical narrative shows helplessness and frustration because a curative therapeutic approach wasn´t available.

Informed consent: clear informed consent was obtained during the patient's hospitalization; she wanted to share her condition in order to raise awareness about the limited treatment options available.

Discussion     

Cor triatriatum was first described by church in 1868 as a left atrium divided by an abnormal septum. The name “triatriatum heart” was given by Borst in 1905 [2]. Cor triatriatum sinister is a rare, congenital cardiac malformation which is present by an abnormal fibromuscular septum leading to a left atria separated into two compartments. The exact etiopathogenesis remains incompletely elucidated; however, the prevailing hypothesis centers on a failure of incorporation of the common pulmonary vein leads to the persistence of a fibromuscular membrane that divides the left atrium into two chambers; proximal and distal. The clinical and physiological impact of cor triatriatum depends on the size and number of fenestrations in the dividing membrane within the left atrium. Cor triatriatum is presented in two forms; a small orifice will have a hemodynamic impact comparable to that of mitral stenosis with an impact on the right heart and pulmonary hypertension, as well as the presence of right-sided congestive signs. However, a large opening will have very minimal hemodynamic and clinical consequences due to unrestricted blood flow between the pulmonary venous chamber and the mitral valve [2].

A systematic review conducted in 2005 by Rudiene et al. including 170 patients with an average age of 43, classified according to the presence or absence of an obstructive membrane showed that the typical progression of the disease is congestive heart failure; 41% of patients had restrictive physiology, accompanied by complications of cardiovascular syndrome, such as atrial fibrillation (32.8%), congestive heart failure (44.3%), and pulmonary hypertension (27.1%). It also reported that the obstructive form is characterized by earlier onset, often associated with other congenital heart defects and leading to more complications such as infections and hemorrhage [3]. In order to analyze the anatomy of the pulmonary veins in detail, to look for abnormal venous return, and to better locate the membrane, 3D reconstructions from cardiac CT or thoracic CT angiography can be very useful [4].

Since the discovery of this pathology, several classifications, particularly of its sinistra form, have been proposed in order to better describe its anatomy, assess its hemodynamic consequences, and guide its medical and surgical management. These include the Loeffler classification, the Lam classification, the modified Lucas classification, and the new Mashadi-Narasimhan-Said classification [5]. Cor triatriatum can remain asymptomatic for a long time and manifest itself through signs of right heart congestion or complications from arrhythmia such as syncope or neurological deficits. On auscultation, the presence of an opening click or loud B1 sound allows it to be differentiated from mitral stenosis. The diagnostic workup in our case included transthoracic echocardiography, which revealed the characteristic fibromuscular membrane. The diagnosis must be supported by various imaging techniques such as transesophageal echocardiography, which offers superior resolution. It allows for a more detailed visualization of the membrane and any fenestrations, and helps to detect associated abnormalities such as atrial septal defect or intra-atrial thrombus [2]. A cardiac computed tomography, or magnetic resonance imaging in order to rule out differential diagnoses such as mitral stenosis, left atrial myxoma, or cardiac thrombus. The aim of treatment is to restore normal blood flow between the pulmonary veins and the mitral valve by removing the obstruction caused by the membrane. Treatment depends on the anatomical type, the severity of the obstruction, and the presence of symptoms.

A systematic review published by Saxena et al. [6] including 25 patients who underwent intra-auricular membrane resection under extracorporeal circulation, demonstrated excellent results, both in the short term with no early mortality and in the long term with a high survival rate of 83% at 10 years after surgery, and optimal functional recovery as evidenced by NYHA class I or II. Robot-assisted correction is an alternative option for patients who do not wish to undergo sternotomy. This technique has been used in some centers and has been described as safe, less traumatic, and with good surgical results [7]. Percutaneous membrane dilation in cor triatriatum sinister is a technique that has been used to a limited extent but is described as an alternative treatment to surgery in very elderly patients at very high surgical risk [8]. In the case we reported, the patient was unable to get the surgery she needed because there wasn´t a cardiothoracic surgical center, and transferring her would not have been possible. Lack of adequate treatment in under-resourced environments has led to a poor prognosis for this patient, a situation that could have been avoided.

Conclusion     

Cor triatriatum sinister is a rare congenital disease whose diagnosis relies primarily on cardiac imaging, particularly echocardiography. This case also brings up serious ethical questions about suffering that could have been prevented and the ongoing unfairness in access to life saving heart care around the world.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Soukaina Aabbar, Wassim Beladel, Khalil Abderrahmane Elbaz, Mehdi Berrajaa, Mohamed El Minaoui: managed the clinical case, critically revised the manuscript. All the authors have read and agreed to the final version of this manuscript.

Figures     

Figure 1: parasternal long-axis view showing the membrane

Figure 2: apical four-chamber view the left atrium divided into two chambers

References